The Routing bit identifies this as being a valid LSA.
It is not carried in the LSA, but is an internal bit
set in the database. When a link fails, the LSA's on
the other side of the link are not necessarily
removed. The Routing Bit is "unset" for those LSA's,
and they are allowed to 'age out'. This means they
are not included in the topology and the prefix
information contained in them will not be installed in
the routing table.
The "Upward" option is actually carried in the LSA.
It is used to prevent routing loops for MPLS VPN's
when OSPF is used for PE-CE connectivity. When an
OSPF route is 'redistributed' from MP-BGP into OSPF,
the "Down bit" is set, so it does not get
redistributed back into MP-BGP on another router.
When this bit is set, it will say "Downward". If you
are not doing OSPF MPLS PE-CE it will never be set.
Hope this helps...
--- Curtis Call <curtiscall@usa.net> wrote:
> There are a couple outputs from the various show ip
> ospf database ... commands
> that I am unfamiliar with and would appreciate
> anyone's input on. What does
> the "Routing bit set for this LSA" refer to, and
> also, I noticed an LSA option
> of "Upward" set on my summary LSAs. Neither of
> these have any relation to the
> OSPF standard that I can gather, so I assume they
> are referring to the Cisco
> implementation.
>
> Any input on this?
>
> Thanks.
>
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This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:12:44 EDT